The present invention relates to a roll for the support and/or transport of hot metal bodies, the roll being internally cooled and may be used, for example, in machines for continuous casting and here particularly for the support of the ingot as it is withdrawn from the mold on a continuous basis. The invention, however, as conceived on the basis of the particular objective, has broader applications and objectives accordingly, because the problem of improving such rolls led to the more general objective of combining two objects in a particular manner, whereby the purpose of the resulting combination entails particulars of and in the objects themselves and the mode and manner of affecting the combining must not only be compatible with the ultimate purpose of the composite object, but the chosen approach should avoid difficulties which may appear due to particular requirements of the result. Among these requirements are the separation of functions which the combined object is to carry out, but which different portions of the object should carry out in an independent, i.e., mutually noninterfering manner. This requirement in turn has led to procedures in the combining of two objects.
Internally cooled rolls for the purposes of transporting and/or supporting hot metal bodies such as ingots are known generally. They consist usually of a core or core-like structure with one or more channels being cut into the core surface. These channels or ducts merge with radial bores which, in turn, terminate in axially oriented bores traversing the journal pin or the like of the roll and by means of which the respective roll is journaled in the stand of the machine. The coolant is fed therefor axially into these journal pins and withdrawn therefrom for distribution throughout the roll, and here particularly the channel and duct system as outlined above. The core of the roll is clad in a sleeve which, for example, is shrunk upon the core thereby covering and closing the cooling channels and ducts.
During operation the roll may support a casting ingot having a temperature of up to and possibly exceeding 1200.degree. C. It is quite clear that the more or less continuous exposure to such hot temperatures under severe load bearing conditions wears on the roll mechanically and/or thermally. It is also easy to understand that a roll being heated more or less continuously in spite of the cooling may be prone to sagging and may assume a distorted configuration. As far as the shrunk sleeve is concerned, it can readily be seen that this differential load on the roll as a whole may cause the sleeve to locally separte from the core. This in turn will lead to parasitic cooling paths so that for a given rate of coolant flow the desired and projected distribution of coolant may no longer may be assured. Therefore, it can readily be seen that in the case of a local separation of the sleeve from the core with a concommitant parasitic flow path there may well appear local areas in the roll which are no longer adequately cooled. This means that the local temperature of the roll in these insufficiently cooled areas may even higher so that any damage is reinforced by positive feed back action. Moreover, the roll serves in part as an object by means of which heat is removed from the object it transports. If now the temperature of the roll in local areas is insufficiently reduced cooling of the ingot engaging that spot will occur only to an insufficient degree. Aside from the detrimental effect of irregular cooling, one has to consider that high thermal differentials render the problem of mechanical loads under hot temperatures even more severe.